Laser probe tip

ABSTRACT

A probe tip for communicating and laterally directing electromagnetic radiation comprises a waveguide, a primary capsule, a compressible member and a malleable secondary capsule. The waveguide is configured to communicate electromagnetic radiation and includes a beveled surface at a distal tip for redirecting electromagnetic radiation in a lateral direction. The primary capsule is attached over the distal tip of the waveguide. The compressible member covers a portion of the primary capsule. The malleable secondary capsule is positioned over the primary capsule and the compressible member, and includes a crimp that compresses the compressible member against the primary capsule and secures the secondary capsule to the primary capsule.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 13/326,813, filed Dec. 15, 2011, which is based on and claimsthe benefit of U.S. provisional patent application Ser. No. 61/423,461,filed Dec. 15, 2010; and U.S. provisional patent application Ser. No.61/423,371, filed Dec. 15, 2010. The content of each of theabove-identified applications is hereby incorporated by reference intheir entirety.

FIELD

Embodiments of the invention are directed to a probe tip for use inmedical laser treatments by communicating and laterally directingelectromagnetic radiation and methods of forming the probe tip.

BACKGROUND

Medical lasers have been used in various practice areas, such as, forexample, urology, neurology, otorhinolaryngology, general anestheticophthalmology, dentistry, gastroenterology, cardiology, gynecology, andthoracic and orthopedic procedures. Generally, these procedures requireprecisely controlled delivery of energy as part of the treatmentprotocol.

Many tissue-ablative laser systems, such as the American Medical SystemsGREENLIGHT® Laser System, utilize a frequency-doubled Nd:YAG laseroperating at 532 nm. This wavelength, provided in a quasi-continuousmode, is used at high power levels for efficient tissue ablation. Thefrequency doubled Nd:YAG laser can be pumped by CW krypton arc lamps andcan produce a constant train of laser light pulses. When ablative powerdensities are used, a superficial layer of denatured tissue is leftbehind. At high powers, 532 nm lasers induce a superficial char layerthat strongly absorbs the laser light and improves ablation efficiency.

Many surgical laser procedures utilize a surgical probe, which generallycomprises an optical fiber and a fiber cap over a distal end of theoptical fiber to form a probe tip. A laser source delivers laser energythrough the optical fiber to the probe tip where the energy isdischarged through the fiber cap and onto desired portions of thetargeted tissue.

The laser energy may be directed laterally from the probe tip byreflecting the laser energy off a polished beveled surface at the distalend of the optical fiber. The fiber cap seals a cavity containing a gas(or vacuum) that maintains the necessary refractive index difference fortotal internal reflection at the beveled surface.

The fiber cap may be protected from tissue adhesion and other causes offiber cap degradation by surrounding the fiber cap with a second cap, asdescribed in U.S. Pat. No. 7,909,817, which is incorporated by referenceherein in its entirety.

There is a continuous need for improvements in laser fiber probe tips,such as improvements that reduce manufacturing costs and increasereliability. Embodiments described herein provide solutions to these andother problems, and offer other advantages over the prior art.

SUMMARY

Embodiments of the invention are directed to a probe tip for use inmedical laser treatments by communicating and laterally directingelectromagnetic radiation. In one embodiment, the probe tip comprises awaveguide, a primary capsule, a compressible member and a malleablesecondary capsule. The waveguide is configured to communicateelectromagnetic radiation and includes a beveled surface at a distal tipfor redirecting electromagnetic radiation in a lateral direction. Theprimary capsule is attached over the distal tip of the waveguide. Thecompressible member covers a portion of the primary capsule. Themalleable secondary capsule is positioned over the primary capsule andthe compressible member, and includes a crimp that compresses thecompressible member against the primary capsule and secures thesecondary capsule to the primary capsule.

In accordance with another embodiment, the probe tip comprises anoptical fiber, a primary capsule and a secondary capsule. The opticalfiber comprises a core for communicating electromagnetic radiation and aprotective layer surrounding the core. The core comprises a distal tipthat extends beyond the protective layer and includes a beveled surfacefor redirecting electromagnetic radiation in a lateral direction. Theprimary capsule is attached over the distal tip of the core. Thesecondary capsule is positioned over the primary capsule and includes aproximal end having a crimp that compresses the protective layer of theoptical fiber and secures the position of the secondary capsule relativeto the primary capsule.

Yet another embodiment is directed to a method. In the method, awaveguide is provided for communicating electromagnetic radiation. Thewaveguide includes a beveled surface at a distal tip for redirectingelectromagnetic radiation in a lateral direction. A primary capsule isattached over the distal tip of the waveguide. A compressible member isplaced on a portion of the primary capsule. A malleable secondarycapsule is positioned over the primary capsule and the compressiblemember. A portion of the secondary capsule is crimped to form a crimp inthe secondary capsule that compresses the compressible member againstthe primary capsule. The crimp secures the secondary capsule to theprimary capsule.

Other features and benefits that characterize embodiments of the presentdisclosure will be apparent upon reading the following detaileddescription and review of the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block drawing of an exemplary surgical lasersystem in accordance with embodiments of the invention.

FIGS. 2 and 3 respectively are isometric assembled and exploded views ofa probe tip in accordance with embodiments of the invention.

FIG. 4 is a side cross-sectional view of a primary capsule of the probetip of FIG. 3 taken generally along line 4-4.

FIGS. 5 and 6 are isometric views of the secondary capsule formed inaccordance with embodiments of the invention.

FIG. 7 is a cross-sectional view of the probe tip of FIG. 2 takengenerally along line 7-7.

FIG. 8 is a side cross-sectional view of a probe tip in accordance withembodiments of the invention.

FIG. 9 is a top view of a probe tip formed in accordance withembodiments of the invention.

FIG. 10 is a cross-sectional view of the probe tip of FIG. 9 takengenerally along line 10-10 and located within a fluid flow channel.

FIGS. 11 and 12 are isometric views of a secondary capsule formed inaccordance with embodiments of the invention.

FIG. 13 is an isometric view of a probe tip formed in accordance withembodiments of the invention.

FIG. 14 is a cross-sectional view of the probe tip illustrated in FIG.13 taken generally along line 14-14.

FIG. 15 is a flowchart illustrating a method in accordance withembodiments of the invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the invention are directed to an apparatus in the form ofa probe tip 100 that is configured to discharge electromagneticradiation 102 from a waveguide, such as an optical fiber 104, asillustrated in the simplified block diagram of a surgical laser system106 provided in FIG. 1. The exemplary system 106 comprises a laserresonator 108. The laser resonator 108 may include a first resonatormirror 110, a second resonator mirror 112 and a laser rod or element114. In one embodiment, the laser element 114 comprises ayttrium-aluminum-garnet crystal rod with neodymium atoms dispersed inthe YAG rod to form a Nd:YAG laser element. Other conventional laserelements 114 may also be used.

The laser element 114 is pumped by a light input 116 from an opticalpump source 118, such as a Kr arc lamp or other conventional pumpsource, to produce laser light or beam 120 at a first frequency. Thelaser resonator 108 also includes a nonlinear crystal 122, such as alithium borate (LBO) crystal or a potassium titanyl phosphate crystal(KTP), for generating a second harmonic of the laser beam 120 emitted bythe laser element 114. The laser beam 120 inside the resonator 108bounces back and forth between the first and second resonator mirrors110 and 112, reflects off a folding mirror 124 and propagates throughthe laser element 114 and nonlinear crystal 122. The laser element 114has optical gain at a certain wavelength and this determines thewavelength of the laser beam 120 inside the resonator 108. Thiswavelength is also referred to as the fundamental wavelength. For theNd:YAG laser element 114, the fundamental wavelength is 1064 nm.

When the laser beam 120 inside the resonator 108 propagates through thenonlinear crystal 122 in a direction away from the folding mirror 124and toward the second resonator mirror 112, a beam 102 ofelectromagnetic radiation at the second harmonic wavelength is outputfrom the crystal 122. The second resonator mirror 112 is highlyreflective at both the fundamental and second harmonic wavelengths andboth beams 120 and 102 propagate back through the nonlinear crystal 122.On this second pass, more beams 102 at the second harmonic wavelengthare produced. For example, the nonlinear crystal 122 can produce a laserbeam 102 having a wavelength of approximately 532 nm (green) when aNd:YAG rod is used as the laser element 114. One advantage of the 532 nmwavelength is that it is strongly absorbed by hemoglobin in blood and,therefore, is useful for cutting, vaporizing and coagulating vasculartissue.

The folding mirror 124 is highly reflective at the fundamentalwavelength and is highly transmissive at the second harmonic wavelength.Thus, the laser beam 102 at the second harmonic passes through thefolding mirror 124 and produces a second harmonic laser beam 102 outsidethe optical resonator 108. An optical coupler 126 is connected to awaveguide, such as an optical fiber 104, to deliver the laser beam 102to a laser delivery probe 128 coupled to a distal end 130 of the opticalfiber 104. In one embodiment, the probe 128 includes the probe tip 100formed in accordance with embodiments of the invention that delivers thebeam 102 to desired tissue for treating a condition of the patient. Inone embodiment, the probe 128 includes an endoscope or cystoscope.

The laser beam 120 inside the resonator 108 at the fundamentalwavelength continues through the laser element 114 and reflects off thefirst resonator mirror 110 which is highly reflective at the fundamentalwavelength. A Q-switch 131 may be used in the resonator 108 to changethe laser beam 120 to a train of short pulses with high peak power.These short pulses increase the conversion efficiency of the secondharmonic laser beam 102 and increase the average power of the laser beam102 outside the resonator 108.

FIGS. 2 and 3 respectively show isometric assembled and exploded viewsof a probe tip 100 in accordance with embodiments of the invention.While embodiments of the probe tip 100 are described as being configuredto direct the electromagnetic energy 102 laterally relative to alongitudinal axis 132 of the waveguide or optical fiber 104, it shouldbe understood that embodiments of the probe tip 100 includeconfigurations in which the electromagnetic energy is directed in otherdirections, such as along the longitudinal axis 132 or at alternativeangles, for example.

In one embodiment, the probe tip comprises a primary capsule 134attached to a distal end 130 of the waveguide 104 and a secondarycapsule 136 over the primary capsule 134. In one embodiment, the primarycapsule in combination with the distal end of the waveguide 104 directsthe laser or electromagnetic energy 102 laterally relative to thelongitudinal axis 134 of the waveguide 104. The secondary capsuleprotects the primary capsule during laser treatments.

FIG. 4 is a side cross-sectional view of the primary capsule 134 and thedistal end 130 of the optical fiber 104 shown in FIG. 3 taken generallyalong line 4-4, in accordance with exemplary embodiments of theinvention. Embodiments of the optical fiber 104 generally comprise anylon jacket 140, a buffer or hard cladding 142, cladding 144 and anoptical fiber core 146. It is understood that other forms of opticalfibers may also be used. The optical fiber core 146 operates as awaveguide through which electromagnetic energy, such as laser beam 102(FIG. 1), travels. In one embodiment, the nylon jacket 140 and at leasta portion of the hard cladding 142 is removed from the distal end 130 toexpose the cladding 144, as illustrated in FIG. 4. In one embodiment, apolished beveled surface 148 is formed at a distal tip 150 of theoptical fiber core 146 in accordance with conventional techniques. Inone embodiment, the polished beveled surface 148 is non-perpendicular tothe longitudinal axis 132 of the optical fiber core 146. Such a beveledsurface 148 operates to reflect the laser light 102 laterally through atransmitting surface 152, as shown in FIG. 4. The beveled surface 148can take on other conventional configurations to direct the output laserbeam 102 in a desired direction.

Embodiments of the fiber cap 134 include a cap body 154 having aninterior cavity 156 and an opening 158 to the interior cavity 156. Thedistal tip 150 of the optical fiber core 146 is received within theinterior cavity 156 through the opening 158. In one embodiment, the capbody 154 seals the interior cavity 156 except at the opening 158. Thegas (or vacuum) interface formed at the beveled surface 148 promotestotal internal reflection of the beam 102 to direct the beam 102 throughthe transmitting surface 152.

In one embodiment, the cap body 154 is bonded to the optical fiber 104by fusing the silica glass cap 134 to the glass cladding 144.Alternatively, the cap body 154 is adhered to the optical fiber 104using a suitable adhesive 160, such as a silicone or fluorocarbonpolymer adhesive, as shown in FIG. 4.

FIGS. 5 and 6 are isometric views of the secondary capsule 136 formed inaccordance with embodiments of the invention. In one embodiment, thesecondary capsule 136 is formed of a malleable material. In oneembodiment, the secondary capsule 136 is formed of metal, such asstainless steel, aluminum, or other suitable metal. In one embodiment,the secondary capsule 136 is a tubular sleeve having an open proximalend 162 and an open distal end 164, as shown in FIG. 5. In oneembodiment, the distal end 164 of the capsule is closed, as illustratedin FIG. 6.

FIG. 7 is a cross-sectional view of the probe tip 100 taken generallyalong lines 7-7 of FIG. 2. Details of the primary capsule 134 and theoptical fiber 104 are not shown in FIG. 7 and other cross-sectionalviews in order to simplify the illustrations. In one embodiment, thesecondary capsule 136 is placed over the primary capsule 134 such thatthe proximal end 162 of the capsule 136 is located on a proximal side ofthe distal tip 150 of the waveguide 104, and the distal end 164 of thecapsule 136 is on a distal side of the distal tip 150. In oneembodiment, an output port 166 in the secondary capsule 136 is alignedwith the transmissive surface 152. In operation, electromagnetic energy102 that is reflected off the beveled surface 148 travels through boththe transmissive surface 152 and the opening 166.

In one embodiment, the secondary capsule 136 is secured to either theprimary capsule 134 and/or the optical fiber 104 by way of one or morecrimps 170 in the secondary capsule 136, as shown in the cross-sectionalviews of the probe tip 100 provided in FIGS. 7 and 8. As used herein,the crimps 170 are formed by creating a deformation, such as a dent, inthe secondary capsule 136 that extends toward the primary capsule 134.In one embodiment, the crimp is formed by squeezing the secondarycapsule.

In one embodiment, the probe tip 100 includes a compressible member 172(FIGS. 3 and 7) that is positioned between the primary capsule 134 andthe secondary capsule 136 such that the compressible member 172 covers aportion of the primary capsule 134. In one embodiment, the compressiblemember 172 generally fills a gap between the inner diameter of thesecondary capsule 136 and the outer diameter of the primary capsule 134.The one or more crimps 170 operate to compress the compressible member172 against the primary capsule 134 to secure the secondary capsule 136to the primary capsule 134.

The compressible member 172 may be formed of any suitable material, suchas silicone. In one embodiment, the compressible member 172 comprises acompressible sleeve (FIG. 3) that is placed over the primary capsule134. Alternatively, the distal end of the primary capsule 134 may be dipcoated in silicone or other compressible material to form thecompressible member 172 thereon.

In one embodiment, the one or more crimps 170 comprise annular crimpsthat are generally coaxial to the longitudinal axis 174 of the primarycapsule 134, as shown in FIGS. 2, 7 and 8. That is, one embodiment ofthe crimps 170 comprises an annular dent in the secondary capsule 136that extends toward the primary capsule 134. In one embodiment, the oneor more crimps 170 may comprise one or more segmented deformations ofthe secondary capsule 136 that extend toward the primary capsule 134. Inone embodiment, the one or more crimps 170 are formed on the distal end164 of the secondary capsule 136, as shown in FIGS. 2, 7 and 8. That is,the crimps 170 are formed on a distal side of the beveled surface 148and the output port 166. In one embodiment, the capsule 136 does notinclude crimps 170 on the proximal end 162.

FIG. 9 is a top view of a probe tip 100 formed in accordance withembodiments of the invention. In one embodiment, the one or more crimps170 are formed only on the proximal end 162 of the capsule 136. That is,the crimps 170 are formed on the proximal side of the beveled surface148 and the output port 166, and the distal end 164 does not include anycrimps 170. In one embodiment, the one or more crimps 170 are formed onboth the proximal end 162 and the distal end 164 of the capsule 136, asshown in FIG. 9. Thus, the crimps 170 may be formed both on the proximaland distal sides of the beveled surface 148 and the output port 166.

In one embodiment, the probe tip 100 is configured to be placed within afluid flow channel during laser treatment operations to assist inpreventing the primary capsule 134 from overheating, which could lead toa failure. FIG. 10 is a cross-sectional view of the probe tip of FIG. 9taken generally along line 10-10 and located within a fluid flow channel180. Embodiments of the fluid flow channel 180 include fluid channelsformed in endoscopes, cystoscopes or other devices.

In one embodiment, the probe tip 100 includes a fluid flow channel 182between the primary capsule 134 and the secondary capsule 136 thatextends from the proximal end 162 to the output port 166, as shown inFIGS. 7, 8 and 10. The fluid flow channel 182 allows fluid (representedby arrows 184) in the channel 180 to travel between the primary capsule134 and the secondary capsule 136. For instance, fluid may enter thechannel 182 at the proximal end 162 and exit at the output port 166, asillustrated in FIG. 10. The flow of the fluid through the channel 182acts to cool the primary capsule 134 and to irrigate the area around thetransmissive surface 152. In one embodiment, the fluid flow channel 182extends between adjacent deformations of the one or more crimps 170formed at the proximal end 162, as shown in FIG. 10.

FIGS. 11 and 12 are isometric views of the secondary capsule 136 formedin accordance with embodiments of the invention. As previouslydiscussed, embodiments of the capsule 136 comprise a tubular sleeve ofmalleable material, such as metal, having an open proximal end 162 andeither an open distal end 164 (FIG. 11) or a closed distal end 164 (FIG.12). Elements having the same or similar labels correspond to the sameor similar elements as those discussed above.

In one embodiment, the secondary capsule includes a crimp 170 at theproximal end 162 that compresses a protective layer of the waveguide oroptical fiber 104, as shown in FIGS. 13 and 14, which respectively arean isometric view of the probe tip 100 and a cross-sectional view of theprobe tip 100 illustrated in FIG. 13 taken generally along line 14-14.The crimp 170 operates to secure the position of the secondary capsule136 relative to the primary capsule 134. In one embodiment, theprotective layer of the optical fiber 104 that is compressed by thecrimp 170 may be the nylon jacket 140, the buffer or hard cladding 142,or other component of the optical fiber 104. In one embodiment, theprotective layer compressed by the crimp 170 is the outer layer of thewaveguide or optical fiber 104, such as the nylon jacket 140, as shownin FIG. 14.

In one embodiment, the secondary capsule 136 includes one or moredeformable members 190 at the proximal end 162 that are used to form thecrimp 170. In one embodiment, the one or more deformable members 190extend from a backside 192 of the proximal end 162 of the capsule 136,as best shown in FIG. 14. In one embodiment, the one or more deformablemembers 190 each comprise a tab 194 extending from the backside 192 ofthe capsule 136. Each tab 194 may be bent toward the backside 192 tocompress the optical fiber 104 against the backside 192, as shown inFIGS. 13 and 14.

In one embodiment, the probe tip 100 includes a fluid flow channel 182extending from the proximal end 162 to the output port 166, as shown inFIG. 14. In one embodiment, a backside 196 of the primary capsule 134,which is opposite a front side 198 that comprises the transmissivesurface 152, is pressed against an interior surface 200 of the backside192 of the secondary capsule 136, as shown in FIG. 14. By positioningthe primary capsule 134 against the backside 192 of the secondarycapsule 136, a gap is formed between the front side 198 of the primarycapsule 134 and the secondary capsule 136 that forms the fluid flowchannel 182. As a result, fluid is allowed to flow into the channel 182from the proximal end 162 and exit through the output port 166 whenplaced in a fluid flow channel, such as channel 180 shown in FIG. 10.

FIG. 15 is a flowchart illustrating a method in accordance withembodiments of the invention. Another embodiment of the invention isdirected to a method. At 202, a waveguide 104, such as an optical fiber,is provided for communicating electromagnetic radiation. The waveguide104 includes a beveled surface 148 at a distal tip 150 for redirectingthe electromagnetic radiation in a lateral direction relative to alongitudinal axis 132 of the waveguide 104. At 204, a primary capsule134 is attached over the distal tip 150 of the waveguide 104, as shownin FIG. 4. At 206, a compressible member 172 (FIGS. 3 and 7) is thenplaced on a portion of the primary capsule 134. A malleable secondarycapsule 136 is then positioned over the primary capsule 134 and thecompressible member 172, at 208. At 210, a portion of the secondarycapsule is crimped to form a crimp 170 that compresses the compressiblemember 172 against the primary capsule 134. The crimp 170 secures thesecondary capsule 136 to the primary capsule 134.

In one embodiment of the method, the secondary capsule 136 has aproximal end 162 on a proximal side of the distal tip 150 and a distalend 164 on a distal side of the distal tip 150. One embodiment of thecrimping step 210 comprises crimping a portion of the distal end 164 ofthe secondary capsule.

In one embodiment, the primary capsule 134 includes a transmissivesurface 152 through which the laterally directed electromagneticradiation is discharged. The secondary capsule includes an output port166 that is aligned with the transmissive surface 152. In the method, afluid flow channel 182 is formed between the primary capsule 134 and thesecondary capsule 136 that extends from a proximal end 162 of thesecondary capsule 136 to the output port 166.

In one embodiment of the method, step 206 is not performed and thecrimping step 210 involves crimping a deformable member 190 at theproximal end 162 to form a crimp 170 that compresses a protective layerof the waveguide or optical fiber 104, as discussed above with regard toFIGS. 11-14. The crimp 170 secures the position of the secondary capsule136 over the primary capsule 134.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

1.-26. (canceled)
 27. An apparatus, comprising: a waveguide having atip; a first capsule including an outlet port, a proximal end over aproximal side of the tip of the waveguide, a distal end over a distalside of the distal tip of the waveguide, and a compressed region on theproximal end to secure the first capsule to the waveguide; and a channelbetween the first capsule and the waveguide, the channel extending fromthe compressed region to the outlet port.
 28. The apparatus of claim 27,wherein the waveguide includes a protective layer and the compressedregion compresses the protective layer.
 29. The apparatus of claim 28,wherein the compressed region includes at least one tab for compressingthe protective layer.
 30. The apparatus of claim 28, wherein theprotective layer includes a nylon jacket, and the compressed regioncompresses the nylon jacket.
 31. The apparatus of claim 27, furtherincluding a second capsule between the first capsule and the waveguide.32. The apparatus of claim 31, wherein: the second capsule includes atransmissive surface through which electromagnetic radiation isdischarged; and the outlet port is aligned with the transmissivesurface.
 33. The apparatus of claim 31, wherein: a back side of thesecond capsule, which is opposite a front side of the second capsule, ispressed against a back side of the first capsule; and the channel isformed between the front side of the second capsule and a front side ofthe first capsule.
 34. The apparatus of claim 27, wherein the firstcapsule is formed of a malleable metal.
 35. The apparatus of claim 27,wherein the waveguide includes a core, wherein the core includes thetip.
 36. The apparatus of claim 35, wherein the tip includes a polishedsurface that is beveled for redirecting electromagnetic radiationlaterally.
 37. The apparatus of claim 27, wherein the compressed regionis a crimp.
 38. An apparatus, comprising: an optical fiber comprising acore and a protective layer surrounding the core, the core comprising adistal tip that extends beyond the protective layer; a primary capsuleover the distal tip of the core; a secondary capsule over the primarycapsule and comprising: an outlet port, wherein a portion of an outercircumferential surface of the primary capsule directly contacts aportion of an inner circumferential surface of the secondary capsule;and a channel disposed between the outer circumferential surface of theprimary capsule and the inner circumferential surface of the secondarycapsule.
 39. The apparatus of claim 38, wherein the channel is disposedcircumferentially around only a portion of the outer circumferentialsurface of the primary capsule.
 40. The apparatus of claim 38, whereinthe secondary capsule includes a compressed region at its proximal endto secure the secondary capsule to the optical fiber.
 41. The apparatusof claim 40, wherein the compressed region is a crimp.
 42. The apparatusof claim 40, wherein an entirety of the channel is distal to thecompressed region.
 43. An apparatus, comprising: an optical fibercomprising a core and a protective layer surrounding the core, the corecomprising a distal tip that extends beyond the protective layer; aprimary capsule over the distal tip of the core; a secondary capsuleover the primary capsule; and a channel disposed between an outercircumferential surface of the primary capsule and an innercircumferential surface of the secondary capsule, wherein the channelextends only partially around the outer circumferential surface of theprimary capsule in a circumferential direction.
 44. The apparatus ofclaim 43, wherein the secondary capsule includes a compressed region atits proximal end to secure the secondary capsule to the optical fiber.45. The apparatus of claim 44, wherein the compressed region is a crimp.46. The apparatus of claim 44, wherein an entirety of the channel isdistal to the compressed region.
 47. The apparatus of claim 44, whereinthe optical fiber includes a protective layer and the compressed regioncompresses the protective layer.